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Mol Cell Biol. 2008 May;28(10):3101-13. doi: 10.1128/MCB.01858-07. Epub 2008 Mar 17.

Silencing of Agamma-globin gene expression during adult definitive erythropoiesis mediated by GATA-1-FOG-1-Mi2 complex binding at the -566 GATA site.

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  • 1Department of Biochemistry and Molecular Biology, MS 3030, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.

Abstract

Autonomous silencing of gamma-globin transcription is an important developmental regulatory mechanism controlling globin gene switching. An adult stage-specific silencer of the (A)gamma-globin gene was identified between -730 and -378 relative to the mRNA start site. A marked copy of the (A)gamma-globin gene inserted between locus control region 5' DNase I-hypersensitive site 1 and the epsilon-globin gene was transcriptionally silenced in adult beta-globin locus yeast artificial chromosome (beta-YAC) transgenic mice, but deletion of the 352-bp region restored expression. This fragment reduced reporter gene expression in K562 cells, and GATA-1 was shown to bind within this sequence at the -566 GATA site. Further, the Mi2 protein, a component of the NuRD complex, was observed in erythroid cells with low gamma-globin levels, whereas only a weak signal was detected when gamma-globin was expressed. Chromatin immunoprecipitation of fetal liver tissue from beta-YAC transgenic mice demonstrated that GATA-1, FOG-1, and Mi2 were recruited to the (A)gamma-globin -566 or (G)gamma-globin -567 GATA site when gamma-globin expression was low (day 18) but not when gamma-globin was expressed (day 12). These data suggest that during definitive erythropoiesis, gamma-globin gene expression is silenced, in part, by binding a protein complex containing GATA-1, FOG-1, and Mi2 at the -566/-567 GATA sites of the proximal gamma-globin promoters.

PMID:
18347053
[PubMed - indexed for MEDLINE]
PMCID:
PMC2423176
Free PMC Article
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